------------------------------------------------------------------------ YITH WooCommerce Compare WordPress Plugin unauthenticated PHP Object injection vulnerability ------------------------------------------------------------------------ Yorick Koster, June 2016 ------------------------------------------------------------------------ Abstract ------------------------------------------------------------------------ A PHP Object injection vulnerability was found in the YITH WooCommerce Compare WordPress Plugin, which can be used by an unauthenticated user to instantiate arbitrary PHP Objects. Using this vulnerability it is possible to execute arbitrary PHP code. ------------------------------------------------------------------------ OVE ID ------------------------------------------------------------------------ OVE-20160803-0006 ------------------------------------------------------------------------ Tested versions ------------------------------------------------------------------------ This issue was successfully tested on the YITH WooCommerce Compare WordPress Plugin version 2.0.9. ------------------------------------------------------------------------ Fix ------------------------------------------------------------------------ This issue is resolved in YITH WooCommerce Compare version 2.1.0. ------------------------------------------------------------------------ Details ------------------------------------------------------------------------ https://sumofpwn.nl/advisory/2016/yith_woocommerce_compare_wordpress_plugin_unauthenticated_php_object_injection_vulnerability.html This issue is possible due to an unsafe call to unserialize() in the __construct() method. The input is taken directly from the yith_woocompare_list cookie as can be seen in the following code fragment: includes/class.yith-woocompare-frontend.php: /** * Constructor * * @return YITH_Woocompare_Frontend * @since 1.0.0 */ public function __construct() { // set coookiename if ( is_multisite() ) $this->cookie_name .= '_' . get_current_blog_id(); // populate the list of products $this->products_list = isset( $_COOKIE[ $this->cookie_name ] ) ? json_decode( maybe_unserialize( $_COOKIE[ $this->cookie_name ] ) ) : array(); It has been confirmed that this issues can be used to execute arbitrary PHP code. ------------------------------------------------------------------------ Summer of Pwnage (https://sumofpwn.nl) is a Dutch community project. Its goal is to contribute to the security of popular, widely used OSS projects in a fun and educational way.